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  <head><title>Great White Shark</title></head><body><h1 id="white-shark">white shark</h1>
<p><strong>white shark</strong> , ( <em>Carcharodon
carcharias</em> ), also called <strong>great<!>
white shark</strong> or <strong>white pointer</strong> ,
any member of the largest living
species of the mackerel sharks (Lamnidae) and one of the most
powerful and dangerous predatory sharks in the world. Starring as the
villain of movies such as <em>Jaws</em> (1975), the white shark is much
maligned and publicly feared. However, surprisingly little is
understood of its life and behaviour.</p>
<h2 id="distribution">Distribution</h2>
<pre><code>white shark ( <span class="hljs-name">Carcharodon</span>
carcharias )
</code></pre><pre><code>White shark ( <span class="hljs-name">Carcharodon</span>
carcharias )
</code></pre><p>White shark populations are
frequently centred in highly
productive temperate coastal
waters (that is, waters
characterized by an abundance of
fishes and marine mammals),
such as off the coasts of the
northeastern and western United
States, Chile, northern Japan, southern Australia, New Zealand,
southern Africa, and the Mediterranean. Some individual white sharks
may travel far out to sea or into tropical waters, but field studies show
that most return to these temperate feeding areas each year.</p>
<h2 id="body-structure">Body structure</h2>
<p>White sharks are large bulky
fishes with a body shaped like a
blunt torpedo. They have a
sharply pointed conical snout,
large pectoral and dorsal fins,
and a strong crescent-shaped tail.
Only the belly of white sharks is
whitish. They have a contrasting
pattern of dark blue, gray, or brown on their back and sides. They are
amazing hunters armed with strong muscles, good eyesight, and a
keen sense of smell. In addition, their massive jaws are armed with</p>
<pre><code><span class="hljs-attribute">white shark</span>
</code></pre><p>large sharply pointed, coarsely serrated teeth. Each tooth is designed
to cut flesh and can easily puncture and shatter bone. The largest fully
grown white sharks do not exceed 6.4 metres (21 feet) in length. Most
weigh between 680 and 1,800 kg (1,500 and 4,000 pounds), but some
weighing more than 2,270 kg (about 5,000 pounds) have been
documented.</p>
<p>Most fish are ectothermic, or cold-blooded, but white sharks have a
complex circulatory system that conserves heat generated through the
contraction of swimming muscles. This heat is distributed throughout
the body to warm its critical regions, giving the white shark a body
temperature higher than the temperature of the surrounding water.
This adaptation, called regional endothermy (which is a type of warm-
bloodedness), allows the animal to be active in water that may be too
cold for other species of predatory sharks.</p>
<h2 id="behaviour">Behaviour</h2>
<h2 id="feeding-habits">Feeding habits</h2>
<pre><code>Newborn white sharks feed <span class="hljs-keyword">on</span>
fishes <span class="hljs-keyword">and</span> other sharks. As they
reach adulthood, their prey
includes sea turtles, seals, sea
lions, porpoises, dolphins, <span class="hljs-keyword">and</span>
small whales. Prey <span class="hljs-keyword">is</span> usually
hunted <span class="hljs-keyword">by</span> ambush, <span class="hljs-keyword">where</span> <span class="hljs-keyword">the</span>
</code></pre><p>shark will attempt to rush the animal by surprise and inflict a sudden
and massive fatal bite. Often this initial rush is so strong that the
intense impact may send the prey out of the water or will send the
shark into the air if it misses the target. The sharks will retire and wait
for the prey to quickly die, giving rise to the terms <em>bite and spit</em> or
<em>bite and wait</em> for this method of attack. White sharks are also
opportunistic scavengers and will feed on the carcasses of whales and
basking sharks; however, they are not indiscriminate.</p>
<h2 id="attacks-on-humans">Attacks on humans</h2>
<p>In the areas where they are most common, white sharks are
responsible for numerous unprovoked, and sometimes fatal, attacks on
swimmers, divers, surfers, kayakers, and even small boats. A white
shark tends to inflict a single bite on its human victim and then
retreat. In many instances, however, the shark does not return for a
second bite. If the victim suffers a moderate bite, he or she may have
time to seek safety. In situations where a large bite occurs, however,
serious tissue and organ damage may result in death. A review of
white shark attacks off the western United States showed that about 7
percent of attacks were fatal, but data from other localities, such as
South Africa, show fatality rates of more than 20 percent. Fatality
rates as high as 60 percent have been recorded from attacks in the
waters off Australia.</p>
<p>Many researchers maintain that attacks on humans stem from the
shark’s curiosity. In contrast, other authorities contend that these</p>
<p>attacks may be the result of the shark mistaking humans for its natural
prey, such as seals and sea lions. It is also possible that white sharks
intend to attack humans where their normal prey may be scarce.</p>
<h2 id="social-behaviour">Social behaviour</h2>
<p>Little is known about the social behaviour and natural history of the
white shark. There appears to be no apparent social structure;
however, there is evidence that some sharks may be territorial and
assume dominance hierarchies around feeding areas. White sharks are
largely solitary, but some pairs have been seen to travel together and
associate for long periods of time. Some individuals may reside
within feeding areas throughout the year, whereas other individuals
may leave the feeding area and migrate widely. For example, some
white sharks off California have been tracked to Hawaii, and some
South African white sharks have been tracked to southern Australia
and back.</p>
<h2 id="reproduction">Reproduction</h2>
<p>Mating has yet to be fully documented in white sharks, but it is
assumed to be similar to internal fertilization in most sharks—that is,
the male inserts his claspers into the cloaca of the female. Courtship
behaviour, if there is any, is unknown. Male white sharks reach sexual
maturity at 3.5 to 4 metres (about 11.5 to 13 feet) in length and about
10 years of age, whereas females reach sexual maturity at 4.5 to 5
metres (about 15 to 16 feet) in length and 12 to 18 years of age.</p>
<pre><code><span class="hljs-keyword">marine </span>food chain
</code></pre><p>Reproduction is viviparous (that is, fertilized eggs are retained within
the body). Prior to birth, the young in the womb may feed on
undeveloped eggs and possibly their unborn siblings. Litters consist of
2 to 10 pups; the newborns are more than 1 metre (about 3.3 feet) in
length. Gestation is thought to take about 12 months, and females are
assumed to give birth in warm temperate and subtropical waters, but
specific nursery areas are unknown.</p>
<h2 id="ecology">Ecology</h2>
<h2 id="role-in-marine-food-chains">Role in marine food chains</h2>
<p>As top predators in marine food
chains, white sharks have few
natural enemies. While it is true
that young white sharks are
sometimes eaten by larger sharks
(including other white sharks),
they have fewer potential
enemies as they grow. Adult white sharks fear few other animals;
however, in at least one documented instance, an adult killer whale
( <em>Orcinus orca</em> ) attacked and killed an adult white shark. The most
profound enemies of the white shark are human beings.</p>
<h2 id="conservation">Conservation</h2>
<p>The white shark has been classified as a vulnerable species by the
International Union for Conservation of Nature (IUCN) since 1996.</p>
<p>Its wide distribution throughout many areas of the ocean has made
comprehensive population surveys difficult; however, catch-rate data
collected by fishery officials worldwide suggest that the species may
be undergoing a decline, but the white shark has only been assessed in
selected regions, such as the Mediterranean Sea, where it is
considered critically endangered.</p>
<p>Humans hunt white sharks for a variety of reasons. They are a good
food fish, and they are caught and sold commercially in many
countries. Because of their impressive size and fabled ferocity, they
are also highly prized sport fish, and their teeth are often treasured as
jewelry. In addition, the jaws of large individuals can fetch thousands
of dollars.</p>
<p>Sharks of all types are also victims of finning, the practice of
harvesting the lateral and dorsal fins and the lower tail fin from a
shark by commercial fishing operations and others worldwide.
Although the United States and several other industrialized countries
have enacted laws that prohibit many shark-finning practices, white
sharks continue to be hunted for their fins. In addition, many white
sharks are caught accidentally in commercial fishing nets each year.
Some of these sharks die in the nets; however, survivors may be killed
intentionally for their fins and other parts by commercial anglers.</p>
<p>White sharks are widespread. However, they are not common. They
fill an important niche as a top predator and may help to keep
populations of marine mammals in balance. Since they are positioned</p>
<pre><code><span class="hljs-attribute">great white shark</span>
</code></pre><p>at the top of the food chain, they
are never abundant. As a result,
the removal of a few individuals
can have a profound effect on
the population. Since they grow
slowly and produce few young,
it takes a long time for
populations to rebound, and harvesting has depleted populations of
these sharks in many areas. Consequently, white sharks are legally
protected in several places (such as Australia, South Africa, and
California) despite their bad reputation. The protection of white
sharks may even have economic benefits. For example, in waters that
contain white sharks, boaters and dive operators earn tens of
thousands of dollars yearly by featuring popular “shark dives” where
guests can see white sharks from the safety of steel cages suspended
in the water. Such a change in image from wanton killer to majestic
predator may assure the future survival of white sharks.</p>
<h2 id="evolution">Evolution</h2>
<p>According to the fossil record, modern white sharks evolved
sometime between 10 million and 4 million years ago, from the
middle of the Miocene Epoch (23 million to 5.3 million years ago)
through the first half of the Pliocene Epoch (5.3 million to 2.6 million
years ago), but their ancestors may date back to at least the Eocene
Epoch (about 56 million to 34 million years ago). Early authorities</p>
<p>maintained that white sharks were descended from the extinct
megalodon ( <em>Carcharocles megalodon</em> , formerly <em>Carcharodon
megalodon</em> )—the largest shark in the fossil record and now
considered to be a member of the megatooth shark family
Otodontidae.</p>
<p>Newer paleontological interpretation is contentious, however, and two
competing hypotheses have developed. In the first hypothesis, modern
white sharks branched off from megatooth sharks to evolve alongside
megalodon and other similar megatooth species. In contrast, the
second hypothesis, based largely on 21st-century fossil finds and
tooth analyses, suggests that modern white sharks descended from a
line of ancient broad-toothed mako sharks—starting with
<em>Carcharodon hastalis</em>. <em>C. hastalis</em> had teeth similar in size and shape
to those of modern white sharks but without serrations. These first
white sharks likely first appeared during the middle of the Miocene
Epoch. (However, some studies suggest that they may have evolved
during the Oligocene Epoch [33.9 million to 23 million years ago].)
Descendent species do not appear to have branched off from <em>C.
hastalis</em>. Instead, white sharks are thought to have gradually
transitioned from <em>C. hastalis</em> to <em>C. hubbelli</em> (between 8 million and 6
million years ago) and then later to <em>C. carcharias</em> (that is, modern
white sharks) in a single evolutionary lineage, or chronospecies.
Fossil discoveries suggest that tooth serrations characteristic of
modern white sharks appeared gradually in the chronospecies,</p>
<p>showing as small serrations in <em>C. hubbelli</em> before becoming fully
developed in <em>C. carcharias</em>.</p>
<p>Douglas Long The Editors of Encyclopaedia Britannica</p>
<pre><!--<code>Citation Information
Article <span class="hljs-string">Title:</span> white shark
Website <span class="hljs-string">Name:</span> Encyclopaedia Britannica
<span class="hljs-string">Publisher:</span> Encyclopaedia Britannica, Inc.
Date <span class="hljs-string">Published:</span> <span class="hljs-number">05</span> December <span class="hljs-number">2022</span>
<span class="hljs-string">URL:</span> <span class="hljs-string">https:</span><span class="hljs-comment">//www.britannica.comhttps://www.britannica.com/animal/white-shark</span>
Access <span class="hljs-string">Date:</span> January <span class="hljs-number">23</span>, <span class="hljs-number">2023</span>
</code>--></pre>
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